Quaternary alloy ScAlGaN: A promising strategy to improve the quality of ScAlN

ScAlN is an emerging ultrawide bandgap semiconductor for next-generation radio frequency electronic devices. Here, we show that the material quality of grown by molecular beam epitaxy can be drastically improved alloying with Ga. The resulting quaternary alloy ScAlGaN exhibits a single-phase wurtzite structure, atomically smooth surface, high crystal quality, sharp interface, and low impurity concentration. Most significantly, oxygen incorporation in found to three four orders magnitude lower compared on AlN templates utilizing similar Sc source. We further demonstrate ScAlGaN/GaN superlattices exhibit clear periodicity interfaces. Moreover, GaN electron mobility transistors sheet density have been realized using as barrier. This work provides viable approach achieving high-quality Sc-III-N semiconductors were not previously possible offers additional dimensions bandgap, polarization, strain, quantum engineering.